The classic “percentage versus number” flaw. If you've taken enough practice exams, then you've definitely encountered this flaw before. In this argument, I'm led to believe that the average 13% profit on a high-end computer model amounts to less than, in dollars, the 25% profit on a low-end computer model. But nope! I won't be tricked by these percentages. We don't know anything about dollars without the actual price of the respective computers. For example, 13% of $3000 (= $390; I'm using the calculator) is more than 25% of $600 (= $150). In short, the argument fails to see that the profit from the high-end computer models can actually exceed the profit from the low-end computer models.

Let's look for this flaw.

A. Bulls-eye! Couldn't have put it better myself. This is exactly the flaw that I was looking for. I'm pretty sure this is it. But for safety, I'll always skim the rest of the answer choices.

B. Nope. The number of computers sold is irrelevant, especially when we have no idea how much each model is selling for. B is gone.

D. Uhm – I don't see the argument making this assumption. But it goes without saying that while maximizing profit is the objective of most businesses (if not all businesses), it may not the sole objective of the computer store.

E. Okay. Now I'm 300% confident that it's A. Future sales and past sales of low-end computers don't mean much when I don't have the actual price of the computer. E is gone.

From Dave: I'm the founder of LSAT Sensei, a boutique LSAT prep and tutoring company based in Chicago. I received my JD from the University of Chicago Law School, and I've been teaching the LSAT for a decade (and counting). I took the LSAT three times: 163, 174, and 180. I had to work my tail off to improve my LSAT score, so I completely embrace the the philosophy that succeeding on the LSAT is a journey. You can tweet me here.

I love how even after wrestling with it for ten years, the LSAT is still fun and intriguing. Back when I was studying to get into law school, my favorite thing about the LSAT was the Games (analytical reasoning) section. I was a natural at it, and I totally got huge ego boosts when I could crush the entire section in 15 minutes or less. But over the years, my favorite thing about the LSAT constantly changes - currently, I get a huge kick out of tearing apart the Logical Reasoning prompts/stimuli. The LSAT authors have a way of digging their own grave.

Please ask questions and/or suggest corrections to anything that seems confusing... we want to make this the best resource we can for LSAT students. We'll have all the June 2013 explanations up as quickly as possible. Thanks for reading. Tell your friends! --nathan

get free resources + discounts.

Bewildered? Let me help.

When should I take the test? When should I start studying? Should I cancel? Should I retake? What if I've already taken some other crappy LSAT class? Logic Games, Logical Reasoning, Reading Comprehension, argghh!

I can make you feel better in about five minutes. Call me! 415-518-0630.Or schedule a time. I'll sort you out.

All actual LSAT questions printed within this work are used with the permission of Law School Admission Council, Inc., Box 2000, Newtown, PA 18940, the copyright owner. LSAC does not review or endorse specific test preparation material or services, and inclusion of licensed LSAT questions within this work does not imply the review or endorsement of LSAC. LSAT is a registered trademark of LSAC.